Device for dressing rock-drill bits



G F NEVIN ETAL DEVICE FOR DRESSING ROCK DRILL 1511's Filed May 9, 1925 ill? Ir M i 'atented Sept. 14, 1326.

UNITED STATES PATENT caries.

GEORGE E. IQ'EVIN AND JOHN GOODLAND, 31%., 0F BUTTE, MONTANA.

DEVICE FOR DRESSING ROCK-DRILL BITS.

Application filed. May 9,

This invention relates to rock drill bits and more particularly to a device for dressing the same.

Rock drills are commonly provided with a central channel through which .water "is forced to clear away rock chips and dust. However, as is well known, the channels become frequently clogged and thereby inoperative.

It is an object of the invention to so form the inner end of the channel as to make it substantially non-plugging;

Another more special object is to provide simple means whereby the inner end of the channel may be effectively constricted to make it non-plugging.

Another special object is the provision of a device which may be associated with a drill bit sharpening device for carrying out the constricting operation.

For a clear understanding of the invention, reference is made to the accompanying drawings in which:

Figs. 1 and 2 are a section and an end view, respectively, of a drill bit embodying the invention;

Fig. 3 is a more or less diagrammatic representation of an arrangement for carrying out the object of the invention;

Fig. 4: is an elevation, partly in section, of a tool more particularly identified with the invention;

Fig. 5 is a sectional view on an enlarged scale of detail shown in Fig. 3; and

Fig. 6 is an end view of an auxiliary part shown in Figs. 3 and 5.

In Figs. 1 and 2 is represented a drill bit 10 consisting of the shank 10, the cutting edges 10 and the channel 10. In the center of the cutting surface of the bit is formed a cup depression 1.1 defining an annular tin 12 swaged inwardly leaving a constricted passage 12%. As appears from the drawing, the fin 12 terminates in' a relatively sharp edge which makes it practically impossible for chips and dust to be packed or wedge in the passage 12 or for larger chips to work back into the channel 10.

An important part of the invention is the mechanism for forming the constriction just described.

In Fig. 8 is represented an arrangement including the usual chuck 13 for holding the drill bit during the sharpening operation and the usual pneumatic hammer or the like 1 1 for operating a sharpening tool.

1925. seriaii-io. eaiec.

These elements are part of the ordinary drill bit sharpening mechanism and do not The drill bit 18 is placed, while hot in the chuck, as shown in Fig. 3, so that it just comes in contact withthe countersunk face of the bushing 16. Air is admitted to the pneumatic hammerand the hammer strikes against he head 17 of the dolly. The latter is driven forward by the hammer until the shoulder formed by the head 17 comes in contact with the bushing which stops the movement of the dolly and the cupping operation is completed.

The cup-shaping portion 17 is forced into the relatively softer steel of the drill bit and swages the resulting annular fin inwardly to a relatively sharp edge while the pin shaped projection 17 uniformly limits the movement of the tin and defines the constricted passage 12.

In practice the operation described ordinarly follows the sharpening operation.

The standard 15 may be permanently fixed I in position. To carry out the sharpening operation, the dolly 17 and the bushing 16 are first removed and after the drill steel is sluirpcned, they are reinserted to carry out the operation as above described.

Lhe recess 19 of the dolly bushing also acts a gauge for the rock drill bit. In practice the outer surface of the cup-forming portion is slightly tapered. The dolly therefore also acts upon the drill steel to force the cutting portions 10 outwardly into engagement with the wall of the recess 19 whereby the cutting edges are centered. It it understood that for each size of drill bit a corresponding bushing is used.

lVe claim:

1. Apparatus for constricting the mouth of the central channel in a-rock drill bit, including a dolly having at its working end a circular cutting edge defining inwardly a howl-shaped recess.

2. Apparatus for constricting the mouth of the central channel in a rock drill bit, including a dolly having at its Working end a circular cutting edge defining inwardly a bowl-shaped recess, and a pin-shaped projection extending centrally from the bottom of the recess.

In a rock drill sharpening devicea means for constricting the central channel in a drill rod, comprising a dolly having at its Working end a circular cutting edge Wedgeshaped in cross-section, the recess de fined by the cut-ting edge having at its outer end a diameter greater than the diameter oi the channel and gradually decreasing toward its bottom.

l. Combination according to claim 3, in which the recess in the dolly is bowl-shaped.

5. Combination according to claim 3, in-

cluding a pin-shaped projection extending centrally'irom the bottom of the recess.

6. Combination according to claim 3, in which the recess in the dolly is bowl-shaped and including a pin-shaped projection er;- tending centrally from the bottom oi the recess.

7. Combination according to claim 3, in cluding a bushing affording a be 'ng for the dolly, and a standard provided with means for clamping the bushing to it.

8. Combination according to claim including a bushing alfording a bearing for the dolly and provided at one end with a drill bit receiving recess, a" d a standard provided With means for clamping the bnsln ing to it.

In testimony whereof, We aliix our signatures.

GEORGE F. SEVEN. JOHN eoonnnnn, JR. 

